The one thing we can generally say with certainty when discussing sport is that the truly great players are almost always taken for granted.

Once they establish an elevated level of play, it often takes a lot to get us excited about someone’s performance. For example, is anyone in Miami or Boston rhapsodizing about the fact that on Friday LeBron James was absolutely unstoppable for three quarters as he was busy scoring 30 of his team’s first 59 points on an evening when most of his teammates might perhaps have been better off volunteering at a soup kitchen?

In these here parts, the man we all too often underappreciate is Kevin Garnett. I think people know that he is playing well. But I’m not sure that enough people know exactly how well, or how historically significant it is that, 17 years into his Hall of Fame career, he remains unique in style and range of big man skill and is still an elite player.

On Friday evening, he played a game unlike any of the previous 1,375 (regular-season and playoff) games he had played since he entered the league as the fifth pick of the 1995 draft for the Minnesota Timberwolves. He did something he never signed up for. He planted his skinny tush in the mosh pit known as the low post and he stayed there, scoring 22 of his 24 points amid a cluster of sturdy Miami bodies.

If you don’t think banging with the likes of Ronny Turiaf and Joel Anthony is work, you try it.

“Listen,’’ said Doc Rivers, “this is exhausting. You get guys grabbing you and holding you, and you’re trying to roll and they’re fronting you. It’s exhausting.’’

Playing low-post basketball is something Kevin Garnett rejected two decades ago. It’s true that, going as far back as Leroy Ellis and Mel Counts in the 1960s, there had been occasional 7-footers who could shoot some jumpers from 15 feet and beyond.

But neither one of them was a star player, and the fact is that when young Kevin Garnett was developing his game in South Carolina and, for his final year of high school, Chicago, most coaches looked at someone his size and said, “I got me a center.’’

But Kevin Garnett was looking into his mirror and saying, “I’m going to be the NBA’s next great forward.’’

In order to pull this off, he had to deliver the goods, so let’s take a look at some of what he has accomplished doing it his way: four-time First Team All-NBA; nine times first-team All-Defensive; 14 All-Star Games; an MVP award; a Defensive Player of the Year award; an All-Star Game MVP; an Olympic gold medal; and one championship ring.

He’s not a wuss; he’s just selective. No namby-pamby guy could lead the NBA in rebounding average four times, as Kevin Garnett has done. It’s just that he came into the league with an advanced concept of the game that featured shooting, rebounding, and, yes, passing. He simply revels in being a facilitator, whether it’s making the pass for an assist or making the key pass-before-the-pass.

In the end, however, the man is a pragmatist, and once the Celtics no longer had Jermaine O’Neal or Chris Wilcox, he understood why he was Doc’s only viable alternative to be the nominal center, or 5 man.

And let’s not kid ourselves, he had spent March, April, and May as a 4 1/2, jumping center and defending the other team’s 5 while playing a face-up version of offense that did not evoke any memories of George Mikan, Kareem Abdul-Jabbar, or even Dwight Howard.

Most of his shots in the Atlanta and Philadelphia series were standard Garnett shots, that is to say face-up jumpers ranging from 15 feet to a step inside the arc, interspersed with a few turnarounds on the baseline.

It was certainly working. He came into Friday night with 10 double-doubles, and some of the games he played were as good as anything he had done in that glorious 2007-08 season. We, of course, took it all for granted. He was just Kevin being Kevin.

Stop right there, because Kevin being Kevin means we expect this 7-foot guy to make more than half his jumpers, night after night, week after week, year after year.

His career regular-season shooting percentage is .499, but that’s not the whole story, because in his five years as a Celtic, he has broken 50 percent every year, with percentages ranging from .503 to .539!

That’s not just amazing; that’s fairly well incomprehensible when you consider the general nature of his shots and his advancing - shhh! don’t tell him I told you - age, which is 36 as of May 19.

Yet what we saw Friday night wasn’t a standard Kevin Being Kevin scenario. It was a complete variation on the theme, and the thing that should not be forgotten is that he did something that was vitally important for his team, however much it was against his nature to do so.

We are in the presence of one of the great players of all time. We can have the debate on just where he fits on The List some other time (top 20 for sure, and top 15 is pretty reasonable). The entire quirky personal package - who does knuckle push-ups in the middle of a game? - is a separate matter.

Focus on Kevin Garnett, the ballplayer. We are not going to have him much longer. We need to savor every second he’s on the floor.

Bob Ryan is a Globe columnist and host of Globe 10.0 on Boston.com. He can be reached at ryan@globe.com.

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